Antioxidant and anti-inflammatory activities of freeze-dried grapefruit phenolics as affected by gum arabic and bamboo fibre addition and microwave pretreatment

Abstract

[EN] BACKGROUND: Recent epidemiological studies have suggested that phenolic compounds present in grapefruit play an important role in the bioactive properties of this fruit. However, the consumption of fresh grapefruit is low. Freeze dried powdered grapefruit can be an alternative to promote this fruit consumption. To improve the quality and stability of the powdered fruit, the addition of encapsulating and anticaking agents can be used. In this work, different grapefruit powders obtained by freeze drying with addition of gum arabic (1.27 g/100 g), and bamboo fibre (0.76 g/100 g) with and without a pre-drying microwave treatment were compared with the fresh and freeze-dried fruit with no carriers added in order to evaluate the effect of these preservation processes on phenolics content and on its antioxidant (DPPH, ABTS and FRAP) and anti-inflamatory (evaluated in RAW 264.7 macrophages) capacities. RESULTS: Freeze drying and gum arabic and bamboo fibre addition significantly increased the total phenolics, and antioxidant and anti-inflammatory activities (by inhibiting NO production of LPS activated RAW 264.7 macrophages) of grapefruit. An additional increase in these parameters was obtained with a microwave pretreatment before freeze-drying. CONCLUSIONS: The combined addition of gum arabic and bamboo fibre to the grapefruit puree and the application of a microwave pretreatment improve the functional properties of the fruit without showing cytotoxicity in vitro.